The synthesis of angular heteroarenochromones based on 7-hydroxy-8-carbonylchromones

Synthesis of linear hetarenochromones based on 7-hydroxy-6-formyl(acetyl)chromones

Fused chromones are attracting increasing attention as novel therapeutic agents due to their wide distribution in nature, effective bioactivities and low toxicity. 6-Carbonyl-7-hydroxychromones proved to be versatile synthons for the synthesis of linear hetarenochromones by annulation of heterocycle to the chromone core. The present review is focused on the syntheses of furo[3,2-g]chromones, pyrano[3,2-g]chromones and some of their N-containing analogues, namely chromeno[6,7-d]isoxazoles, pyrano[3’,2’:6,7]chromeno[4,3-b]pyridine-5,11-diones and pyrano[3’,2’:6,7]chromeno[4,3-c]pyridine-5,11-diones based on the 7-hydroxy-6-formylchromones or 7-hydroxy-6-acetylchromones and shows the current state of research to date. The methods for the synthesis of the starting 7-hydroxy-6-formylchromones and 7-hydroxy-6-acetylchromones have been also mentioned. The biological activity of naturally occurring and modified synthetic linear hetarenochromones has been also represented.

Synthesis of chromones, annulated with oxygen-containing heterocycles with two hetero atoms at C(7)-C(8) bond

The present review represented the advanced synthetic strategies for chromones annulated at the C(7)-C(8) bond with five-membered, six-membered, and seven-membered oxygen-containing heterocycles with two heteroatoms, such as 6H-[1,3]dioxolo[4,5-h]chromen-6-one, 2,3-dihydro-7H-[1,4]dioxino[2,3-h]chromen-7-one, 3,4-dihydro-2H,8H-[1,4]dioxepino[2,3-h]chromen-8-one, 2,3-dihydro-1H,7H-chromeno[7,8-b][1,4]oxazin-7-one, 4H,12H-pyrano[2,3-a]phenoxazine-4-one and 9,10-dihydro-4H,8H-chromeno[8,7-e][1,3]oxazin-4-one. The biological activity of naturally occurring and modified synthetic fused hetarenochromones has been also highlighted.

The synthesis of angular heteroarenochromones based on 7-hydroxy-8-carbonylchromones

The present review highlights advanced strategies to the synthesis of the chromones annulated with O- and N-containing heterocycles at C(7)-C(8) bond. Due to the prevalence of such motives in different kinds of natural flavonoids and some alkaloids, fused chromones have attracted a great deal of attention so far. On the other hand a wide range of biological activities is displayed by the compounds of this type both among naturally occurring flavonoids and their synthetic analogues. 8-Carbonyl-7-hydroxychromones proved to be versatile synthones for the synthesis of angular hetarenochromones via approach of annulation of a heterocycle to the chromone core. It also addresses the question of the biological activity of naturally occurring and fused synthetic hetarenochromones.